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Technical Configuration
The IP Datagram with Header, Its Type-of-Service field, & DiffServ
bits =>
0
4
8
VERS
HLEN
IDENTIFICATION
TIME TO LIVE
PROTOCOL
IP OPTIONS (if any)
The TOS field consists of eight bits, of which only the first six are used. These six bits are called the "Differentiated Service
Codepoint" or DSCP bits.
The Type of Service or "TOS" field
0
1
2
PRECEDENCE
The three 'Precedence' bits have eight values, 0-7, ranging from "normal" precedence (value of 0) to "network control"
(value of 7). When set, the D bit requests low delay, the T bit requests high throughput, and the R bit requests high
reliability.
Routers that support DiffServ can examine the six DSCP bits and prioritize the packet based on the DSCP value. The
DiffServ Parameters fields in the Ethernet/IP Parameters screen allow you to configure the DSCP bits to values supported by
the router. Specifically, the Voip Media PHB field relates to the prioritizing of audio packets (RTP and RTCP packets) and
the Call Control PHB field relates to the prioritzing of non-audio packets (packets concerning call set-up and tear-down,
gatekeeper registration, etc.).
The Call Control PHB parameter defaults to 34 decimal (22 hex; 100010 binary – consider vis-à-vis TOS field above) for
Assured Forwarding behavior. The Voip Media PHB parameter defaults to the value 46 decimal (2E hex; 101110 binary –
consider vis-à-vis TOS field above). To disable DiffServ, configure both fields to 0 decimal.
Field Name
FTP Server
Enable
16
19
TYPE OF
SERVICE
FLAGS
SOURCE IP ADDRESS
DESTINATION IP ADDRESS
DATA
...
3
4
5
D
T
R
Ethernet/IP Parameter Definitions (cont'd)
Values
FTP Parameter fields
Y/N
Default = disabled
See "FTP Server
File Transfers" in
Operation &
Maintenance
chapter.
24
TOTAL LENGTH
FRAGMENT OFFSET
HEADER CHECKSUM
PADDING ...
end of header
6
7
unused
Description
TalkAnytime unit has an FTP Server function
so that firmware and other important
operating software files can be transferred to
the unit via the network.
78
TalkAnytime User Guide
31
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